There was telling moment during the CNN Republican presidential debate: Asked about the possibility of repealing George W. Bush’s Medicare prescription-drug benefit, which is adding some $17 trillion to Medicare’s unfunded liabilities, every one of the candidates pledged varying degrees of fealty to the program. No one came out for significantly cutting this vestige of Bush-style big-government conservatism, let alone repealing it. This put the current crop of Republicans to the left of John McCain, who at least campaigned in favor of means-testing the program in 2008.

The failure to stand up against one of the Bush administration’s most obvious mistakes is not just a case of hypocrisy; it is part of a disturbing trend toward ducking the tough decisions on budget cutting among the Republican aspirants. For all the sound and fury, and the charges and countercharges surrounding entitlement reform, the GOP candidates have been remarkably reluctant to put forward actual proposals.

Former Massachusetts governor Mitt Romney, for example, has been attacking Texas governor Rick Perry over Social Security from the left, praising the program as “an essential federal program,” that has been a “success” for more than 70 years. But for all his criticism of Perry, Romney has been much vaguer about his own plans for reform. At times he has sounded almost like Obama, suggesting that there are lots of reform ideas — raising the retirement age, means testing, changing the wage-price indexing formula — that are “on the table,” but not actually endorsing any of them. One reform that Romney has taken off the table is allowing younger workers to privately invest a portion of their payroll taxes through personal accounts. In his book, No Apology, Romney endorses so-called “add on” accounts, allowing workers to save in addition to Social Security, but not carving out a portion of their current taxes. “Given the volatility of investment values that we have just experienced, I would prefer that individual accounts were added to Social Security, not diverted from it,” Romney wrote.

The Republican candidates all talk about reducing government spending. But they cannot do that unless they commit to real entitlement reform.

On Medicare, Romney has avoided specifics as well, praising Paul Ryan’s proposed reforms for example as “taking important strides in the right direction,” but not endorsing them.

For his part, Governor Perry has been forthright about the flaws of Social Security but has offered nothing in the way of a proposal for reform. As Romney has pointed out endlessly, Perry suggested in his book that Social Security might be returned to the states. But Perry has since disavowed that idea, claiming that he was only referring to state employees, some 7 million of whom are currently outside the Social Security system. Perry has also praised the privatized system for public employees in Galveston and two other Texas counties, suggesting that he might be open to some type of private investment option. But “suggesting” is as far as he goes.

On Medicare, Perry has been equally murky. At times, he has suggested that we should “transition away from” the current Medicare system, but without saying what we should transition to. His aides point out that Perry has only recently joined the race and hasn’t had time to develop specific proposals. But given his fiery talk on the issues, until he does he will seem more hat than cattle.

Rep. Michelle Bachmann has also largely tried to have it both ways on entitlement reform. She voted for the Ryan plan in Congress but promptly put out a statement distancing herself from it, claiming that her vote came with an asterisk. On Social Security, Bachmann once called the program a “monstrous fraud,” but has now joined Romney in attacking Perry’s “Ponzi scheme” description. She says that a key difference between her and Perry is that she believes Social Security “is an important safety net and that the federal government should keep its promise to seniors.” But with Social Security currently facing more than $20 trillion in unfunded liabilities, the question is how it will keep that promise.

Second-tier candidates, with less to lose, have been more willing to spell out their proposals. Businessman Herman Cain, for example, supports both the Ryan plan and Chilean-style personal accounts for Social Security. Former Pennsylvania senator Rick Santorum takes similar positions, as does former New Mexico governor Gary Johnson. Former Utah governor Jon Huntsman has endorsed the Ryan plan but has not spelled out his views on Social Security reform. Newt Gingrich, on the other hand, has focused on cutting “fraud, waste, and abuse,” rather than fundamentally altering the structure of those programs. Ever the iconoclast, Rep. Ron Paul opposes both the Ryan plan and personal accounts for Social Security, since he opposes a federal role in either health care or retirement on principle.

The facts are both simple and frightening. The unfunded liabilities of Social Security and Medicare run between $50 trillion and $110 trillion. Those two programs, along with Medicaid, are the primary drivers of our future indebtedness. In fact, by 2050, those three programs alone will consume 18.4 percent of GDP. If one assumes that revenues return to and stay at their traditional 18 percent of GDP, then those three programs alone will consume all federal revenues. There would not be a single dime available for any other program of government, from national defense to welfare.

The Republican candidates all talk about reducing government spending. But they cannot do that unless they commit to real entitlement reform. There’s time, and lots of debates, to hear specifics from them. But so far, the omens are not auspicious